The present invention relates to electric household appliances for processing foodstuffs, comprising a principal body enclosing a motor group and its control means, and a working accessory provided with a tool adapted to be driven by the motor group.
The invention relates more particularly to a safety device comprising a first means disposed in the principal body of the apparatus and acting on the control means of the motor group, and a second means connected to the accessory so as to prevent the operation of the apparatus if the accessory is not in place.
In apparatus of this type, a solution currently used for safety devices consists in providing a mechanical device that acts on a switch disposed between the electrical supply and the motor group of the apparatus. These mechanical devices have several drawbacks: they can be disabled rather simply by an unscrupulous user; the mechanical elements can wear and become inoperative; they are sensitive to dirt. Moreover, for certain types of accessories it is difficult to design a mechanical safety which will be aesthetically acceptable. For example, for a transparent mixer bowl of elongated shape enclosed by a cover, it is difficult to design a mechanical safety device for locking the cover, without this device being visible.
Another solution, described in French patent 90 00930 filed Jan. 26, 1990 by the applicant, consists in using a Hall effect detector adapted to detect a magnet secured to the accessory. This type of safety requires a particular construction of the apparatus, because the distance of interaction between the magnet and the detector is small. Moreover, safety is not absolute, because the detector can be maliciously evaded by using a suitable magnet.
The present invention has for its object to eliminate these drawbacks and to provide particularly a reliable safety device which is easily integrated into existing electric household appliances.